LCD
panel for high voltage power supply to the lamp power supply, it will
transform the high-frequency DC low-voltage power supply high voltage
power supply to light the lamp, belonging to power conversion devices,
easy to heat, it is easier bad. There are many customer’s screen dark,
and incredibly anxious, thinking that bad screen, or the host goes
wrong, drugs everywhere, grasping side asked did not know that that is a
small high-pressure plate is broken.
In fact, the high-pressure
plate is a switching power supply, except in relation to the ordinary
switching power supply, it’s less post-rectification filtering part of
the class, while the focus on high-frequency high-voltage
transformation. It’s low-voltage DC on the motherboard (in general, is
more than V, or 5V) through the switch into a high-frequency alternating
current chopper, and then high-frequency step-up transformer in order
to achieve light lamp voltage.
Read also:Detailed Blinking Error Code of Panasonic TV
Inverter power and signal from the
motherboard, generally there are so Jigen line connected to the
motherboard: power V +, the power to G, switch signal S, luminance
signal F (and some not). When the computer starts, the power supply,
switching signal S to start switching oscillator circuit, switch to
work, transformer voltage boost lit lamp.
Visible, high-pressure board a bad device is just a few easy: oscillation circuit, switch, transformer.
However,
in the maintenance process, we found that many screen dark phenomenon
is not due to pressure plate itself, but others are due to damage to the
motherboard connection, some motherboard itself is bad, can not give
high-voltage power supply board.
Example:
1. Toshiba 3000
computer screen light when the dark. Lamp power and high-pressure plate
does not match the high-voltage plate power is too small, start heating
over-current protection.
2. Purple computer (there is a Twinhead,
are the same manufacturer OEM), they can not machine, the computer
thought it was a bad motherboard, and after testing, the final result
for the high-pressure plate is broken. Replacement of high-pressure
plate, over a period of time, failure to reproduce the high-pressure
board has burned. Was originally due to high-voltage plate power is too
small!
Therefore, high-pressure section of the LCD screen lamp
failure and are closely linked, it may be caused by high-pressure lamp
of the damage, is also possible that high-pressure section of the PWM,
or ignition coil damage.